基于岩石特性的扎哈泉油田缝网压裂可行性分析

针对低孔、低渗油藏特点,青海扎哈泉油田采用缝网压裂技术进行了增产改造。监测结果显示部分井存在单裂缝扩展现象,表明缝网压裂技术存在适应性问题。分析了单井岩性特征对缝网压裂工艺的影响因素,重点研究了储层的岩石矿物组分、力学参数和天然裂缝。结果显示:研究区储层具有高脆性指数、高弹性模量、低泊松比的特征;储层裂隙以微米级孔隙为主,纳米级孔隙不发育,且孔隙连通性差;天然裂缝发育,有效油层段天然裂缝密度为1.25条/m。建立了三因素综合分析方法,并对扎哈泉油田某井进行了缝网压裂试验,监测结果显示达到了缝网压裂效果。研究成果可为油井缝网压裂技术应用提供依据。

Feasibility analysis on the fracture network fracturing based on the rock characteristics in Zhahaquan Oilfield

Faced with the characteristics of the low-porosity and low-permeability oil reservoir, fracture-network fracturing technique was adopted to increase the production in Qinghai Zhahaquan Oilfield. The monitored results show that there exit single fracture propagation phenomena in some wells, thus the adaptability problem is displayed for this kind of the technique. The influencing factors of the lithological characteristics of the single well on the fracture-network fracturing technology were analysed, the study focuses on the rock mineral compositions, mechanical parameters and natural fractures of the reservoir. The results show that the reservoirs in the study region are characterized by high brittleness index, high elasticity modulus and low Poisson’s ratio;the reservoir fractures are dominated by micron-scale pore, and the nano-scale pore is undeveloped, and moreover the pore connectivity is rather poor;the natural fractures are well developed, and furthermore the density of the natural fractures in the effective oil reservoir is1.25 piece/m. The three-factor comprehensive analyzing method was established, and a well in Zhahaquan Oilfield was tested by the fracturing, the monitored results show that the fractured effects have achieved. The research results can provide the evidence for the application of the fracture-network fracturing technique in the oil wells.